The thunderclouds called cumulonimbus stretch over several kilometers. They composed of positively charged ice crystals at the top, and of negatively charged droplets at the base. 80 to 90% of lightning strokes in Europe are negative whereas in other regions, the proportion of positively charged strokes is higher. When a cumulonimbus is created, the ground electrical field rises to values close to 20kV/m whereas the various high points create natural ionization ( Figure 1 ).

Several tracers are produced at the core of the cloud and they travel to the ground by successive steps. When these descending leaders come closer, the ionization of the high points increases and produces ascending tracers ( Figure 2 ). The meeting of both tracers creates an ionized path down which the cloud discharges it electric charge ( Figure 3 ).

THE LIGHTNING CONDUCTOR

The IONOSTAR Early Streamer Emission lightning conductor principle is to artificially create, with an ionizing device, a powerful ascending tracers and thus produce a privileged lightning impact point on its tip whatever the thundercloud polarity maybe ( Figure 4 & 5 ).

THE SECOND GENERATION

The patented lightning conductor IONOSTAR, like the previous model, works on the energy of the electrical field from the thundercloud descending tracers. Its ionizing device captures the ambient electromagnetic field, this rising potential is simultaneously amplified by a device based on spark gaps. The resulting ionization starts a significant advance on the startup discharge for positive as well as for negative discharges.

When the lightning stroke reaches the rod, the discharge current is deviated to an electrode directly connected to the earth protecting the ionizing device of the lightning conductor IONOSTAR. The active parts of this device being shunted, it can resist the strongest strokes.